X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=ea9fc55468d678ff1b0b4e70862d70f33da83073;hp=58a82d9dc24699cf04ad76b8b3dae4d40a44ec71;hb=7ea38e980b414682beb07eafe5962c0cc6a5713d;hpb=339bf9b7e1bf812b1756bb79c1ba7d7b5ea4dd9a diff --git a/src/search.cpp b/src/search.cpp index 58a82d9d..ea9fc554 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -47,7 +47,7 @@ namespace { const bool FakeSplit = false; // Different node types, used as template parameter - enum NodeType { NonPV, PV }; + enum NodeType { Root, PV, NonPV, SplitPointPV, SplitPointNonPV }; // RootMove struct is used for moves at the root of the tree. For each root // move, we store two scores, a node count, and a PV (really a refutation @@ -88,44 +88,11 @@ namespace { void init(Position& pos, Move searchMoves[]); void sort() { insertion_sort(begin(), end()); } - void sort_multipv(int n) { insertion_sort(begin(), begin() + n); } + void sort_first(int n) { insertion_sort(begin(), begin() + n); } int bestMoveChanges; }; - // MovePickerExt template class extends MovePicker and allows to choose at compile - // time the proper moves source according to the type of node. In the default case - // we simply create and use a standard MovePicker object. - template struct MovePickerExt : public MovePicker { - - MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) - : MovePicker(p, ttm, d, h, ss, b) {} - - RootMoveList::iterator rm; // Dummy, needed to compile - }; - - // In case of a SpNode we use split point's shared MovePicker object as moves source - template<> struct MovePickerExt : public MovePicker { - - MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) - : MovePicker(p, ttm, d, h, ss, b), mp(ss->sp->mp) {} - - Move get_next_move() { return mp->get_next_move(); } - - RootMoveList::iterator rm; // Dummy, needed to compile - MovePicker* mp; - }; - - // In case of a Root node we use RootMoveList as moves source - template<> struct MovePickerExt : public MovePicker { - - MovePickerExt(const Position&, Move, Depth, const History&, SearchStack*, Value); - Move get_next_move(); - - RootMoveList::iterator rm; - bool firstCall; - }; - /// Constants @@ -189,9 +156,9 @@ namespace { // Reduction lookup tables (initialized at startup) and their access function int8_t Reductions[2][64][64]; // [pv][depth][moveNumber] - template inline Depth reduction(Depth d, int mn) { + template inline Depth reduction(Depth d, int mn) { - return (Depth) Reductions[PV][Min(d / ONE_PLY, 63)][Min(mn, 63)]; + return (Depth) Reductions[PvNode][Min(d / ONE_PLY, 63)][Min(mn, 63)]; } // Easy move margin. An easy move candidate must be at least this much @@ -233,22 +200,12 @@ namespace { Move id_loop(Position& pos, Move searchMoves[], Move* ponderMove); - template + template Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth); - template + template Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth); - template - inline Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) { - - return depth < ONE_PLY ? qsearch(pos, ss, alpha, beta, DEPTH_ZERO) - : search(pos, ss, alpha, beta, depth); - } - - template - Depth extension(const Position& pos, Move m, bool captureOrPromotion, bool moveIsCheck, bool* dangerous); - bool check_is_dangerous(Position &pos, Move move, Value futilityBase, Value beta, Value *bValue); bool connected_moves(const Position& pos, Move m1, Move m2); Value value_to_tt(Value v, int ply); @@ -266,6 +223,43 @@ namespace { void poll(const Position& pos); void wait_for_stop_or_ponderhit(); + // MovePickerExt template class extends MovePicker and allows to choose at compile + // time the proper moves source according to the type of node. In the default case + // we simply create and use a standard MovePicker object. + template struct MovePickerExt : public MovePicker { + + MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) + : MovePicker(p, ttm, d, h, ss, b) {} + + RootMove& current() { assert(false); return Rml[0]; } // Dummy, needed to compile + }; + + // In case of a SpNode we use split point's shared MovePicker object as moves source + template<> struct MovePickerExt : public MovePickerExt { + + MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) + : MovePickerExt(p, ttm, d, h, ss, b), mp(ss->sp->mp) {} + + Move get_next_move() { return mp->get_next_move(); } + MovePicker* mp; + }; + + template<> struct MovePickerExt : public MovePickerExt { + + MovePickerExt(const Position& p, Move ttm, Depth d, const History& h, SearchStack* ss, Value b) + : MovePickerExt(p, ttm, d, h, ss, b) {} + }; + + // In case of a Root node we use RootMoveList as moves source + template<> struct MovePickerExt : public MovePicker { + + MovePickerExt(const Position&, Move, Depth, const History&, SearchStack*, Value); + RootMove& current() { return Rml[cur]; } + Move get_next_move() { return ++cur < (int)Rml.size() ? Rml[cur].pv[0] : MOVE_NONE; } + + int cur; + }; + // Overload operator<<() to make it easier to print moves in a coordinate // notation compatible with UCI protocol. std::ostream& operator<<(std::ostream& os, Move m) { @@ -288,6 +282,51 @@ namespace { return os; } + // extension() decides whether a move should be searched with normal depth, + // or with extended depth. Certain classes of moves (checking moves, in + // particular) are searched with bigger depth than ordinary moves and in + // any case are marked as 'dangerous'. Note that also if a move is not + // extended, as example because the corresponding UCI option is set to zero, + // the move is marked as 'dangerous' so, at least, we avoid to prune it. + template + FORCE_INLINE Depth extension(const Position& pos, Move m, bool captureOrPromotion, + bool moveIsCheck, bool* dangerous) { + assert(m != MOVE_NONE); + + Depth result = DEPTH_ZERO; + *dangerous = moveIsCheck; + + if (moveIsCheck && pos.see_sign(m) >= 0) + result += CheckExtension[PvNode]; + + if (pos.type_of_piece_on(move_from(m)) == PAWN) + { + Color c = pos.side_to_move(); + if (relative_rank(c, move_to(m)) == RANK_7) + { + result += PawnPushTo7thExtension[PvNode]; + *dangerous = true; + } + if (pos.pawn_is_passed(c, move_to(m))) + { + result += PassedPawnExtension[PvNode]; + *dangerous = true; + } + } + + if ( captureOrPromotion + && pos.type_of_piece_on(move_to(m)) != PAWN + && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) + - pos.midgame_value_of_piece_on(move_to(m)) == VALUE_ZERO) + && !move_is_special(m)) + { + result += PawnEndgameExtension[PvNode]; + *dangerous = true; + } + + return Min(result, ONE_PLY); + } + } // namespace @@ -304,8 +343,8 @@ void init_search() { { double pvRed = log(double(hd)) * log(double(mc)) / 3.0; double nonPVRed = 0.33 + log(double(hd)) * log(double(mc)) / 2.25; - Reductions[PV][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(ONE_PLY)) : 0); - Reductions[NonPV][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(ONE_PLY)) : 0); + Reductions[1][hd][mc] = (int8_t) ( pvRed >= 1.0 ? floor( pvRed * int(ONE_PLY)) : 0); + Reductions[0][hd][mc] = (int8_t) (nonPVRed >= 1.0 ? floor(nonPVRed * int(ONE_PLY)) : 0); } // Init futility margins array @@ -541,7 +580,7 @@ namespace { // research with bigger window until not failing high/low anymore. do { // Search starting from ss+1 to allow calling update_gains() - value = search(pos, ss+1, alpha, beta, depth * ONE_PLY); + value = search(pos, ss+1, alpha, beta, depth * ONE_PLY); // Write PV back to transposition table in case the relevant entries // have been overwritten during the search. @@ -552,8 +591,6 @@ namespace { if (StopRequest) break; - assert(value >= alpha); - // In case of failing high/low increase aspiration window and research, // otherwise exit the fail high/low loop. if (value >= beta) @@ -663,9 +700,13 @@ namespace { // all this work again. We also don't need to store anything to the hash table // here: This is taken care of after we return from the split point. - template + template Value search(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) { + const bool PvNode = (NT == PV || NT == Root || NT == SplitPointPV); + const bool SpNode = (NT == SplitPointPV || NT == SplitPointNonPV); + const bool RootNode = (NT == Root); + assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta > alpha && beta <= VALUE_INFINITE); assert(PvNode || alpha == beta - 1); @@ -676,14 +717,15 @@ namespace { StateInfo st; const TTEntry *tte; Key posKey; + Bitboard pinned; Move ttMove, move, excludedMove, threatMove; Depth ext, newDepth; ValueType vt; Value bestValue, value, oldAlpha; Value refinedValue, nullValue, futilityBase, futilityValueScaled; // Non-PV specific - bool isPvMove, inCheck, singularExtensionNode, givesCheck, captureOrPromotion, dangerous, isBadCap; + bool isPvMove, inCheck, singularExtensionNode, givesCheck, captureOrPromotion, dangerous; int moveCount = 0, playedMoveCount = 0; - int threadID = pos.thread(); + Thread& thread = Threads[pos.thread()]; SplitPoint* sp = NULL; refinedValue = bestValue = value = -VALUE_INFINITE; @@ -692,8 +734,8 @@ namespace { ss->ply = (ss-1)->ply + 1; // Used to send selDepth info to GUI - if (PvNode && Threads[threadID].maxPly < ss->ply) - Threads[threadID].maxPly = ss->ply; + if (PvNode && thread.maxPly < ss->ply) + thread.maxPly = ss->ply; if (SpNode) { @@ -703,15 +745,13 @@ namespace { threatMove = sp->threatMove; goto split_point_start; } - else if (Root) - bestValue = alpha; // Step 1. Initialize node and poll. Polling can abort search ss->currentMove = ss->bestMove = threatMove = (ss+1)->excludedMove = MOVE_NONE; (ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO; - (ss+2)->killers[0] = (ss+2)->killers[1] = (ss+2)->mateKiller = MOVE_NONE; + (ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE; - if (threadID == 0 && ++NodesSincePoll > NodesBetweenPolls) + if (pos.thread() == 0 && ++NodesSincePoll > NodesBetweenPolls) { NodesSincePoll = 0; poll(pos); @@ -719,16 +759,18 @@ namespace { // Step 2. Check for aborted search and immediate draw if (( StopRequest - || Threads[threadID].cutoff_occurred() - || pos.is_draw() - || ss->ply > PLY_MAX) && !Root) + || pos.is_draw() + || ss->ply > PLY_MAX) && !RootNode) return VALUE_DRAW; // Step 3. Mate distance pruning - alpha = Max(value_mated_in(ss->ply), alpha); - beta = Min(value_mate_in(ss->ply+1), beta); - if (alpha >= beta) - return alpha; + if (!RootNode) + { + alpha = Max(value_mated_in(ss->ply), alpha); + beta = Min(value_mate_in(ss->ply+1), beta); + if (alpha >= beta) + return alpha; + } // Step 4. Transposition table lookup // We don't want the score of a partial search to overwrite a previous full search @@ -742,10 +784,8 @@ namespace { // At PV nodes we check for exact scores, while at non-PV nodes we check for // a fail high/low. Biggest advantage at probing at PV nodes is to have a // smooth experience in analysis mode. - if ( !Root - && tte - && (PvNode ? tte->depth() >= depth && tte->type() == VALUE_TYPE_EXACT - : ok_to_use_TT(tte, depth, beta, ss->ply))) + if (tte && (PvNode ? tte->depth() >= depth && tte->type() == VALUE_TYPE_EXACT + : ok_to_use_TT(tte, depth, beta, ss->ply))) { TT.refresh(tte); ss->bestMove = ttMove; // Can be MOVE_NONE @@ -821,7 +861,8 @@ namespace { pos.do_null_move(st); (ss+1)->skipNullMove = true; - nullValue = -search(pos, ss+1, -beta, -alpha, depth-R*ONE_PLY); + nullValue = depth-R*ONE_PLY < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -beta, -alpha, depth-R*ONE_PLY); (ss+1)->skipNullMove = false; pos.undo_null_move(); @@ -860,7 +901,37 @@ namespace { } } - // Step 9. Internal iterative deepening + // Step 9. ProbCut (is omitted in PV nodes) + // If we have a very good capture (i.e. SEE > seeValues[captured_piece_type]) + // and a reduced search returns a value much above beta, we can (almost) safely + // prune the previous move. + if ( !PvNode + && depth >= RazorDepth + ONE_PLY + && !inCheck + && !ss->skipNullMove + && excludedMove == MOVE_NONE + && abs(beta) < VALUE_MATE_IN_PLY_MAX) + { + Value rbeta = beta + 200; + Depth rdepth = depth - ONE_PLY - 3 * ONE_PLY; + + assert(rdepth >= ONE_PLY); + + MovePicker mp(pos, ttMove, H, Position::see_value(pos.captured_piece_type())); + pinned = pos.pinned_pieces(pos.side_to_move()); + + while ((move = mp.get_next_move()) != MOVE_NONE) + if (pos.pl_move_is_legal(move, pinned)) + { + pos.do_move(move, st); + value = -search(pos, ss+1, -rbeta, -rbeta+1, rdepth); + pos.undo_move(move); + if (value >= rbeta) + return value; + } + } + + // Step 10. Internal iterative deepening if ( depth >= IIDDepth[PvNode] && ttMove == MOVE_NONE && (PvNode || (!inCheck && ss->eval + IIDMargin >= beta))) @@ -868,25 +939,25 @@ namespace { Depth d = (PvNode ? depth - 2 * ONE_PLY : depth / 2); ss->skipNullMove = true; - search(pos, ss, alpha, beta, d); + search(pos, ss, alpha, beta, d); ss->skipNullMove = false; - ttMove = ss->bestMove; tte = TT.probe(posKey); + ttMove = tte ? tte->move() : MOVE_NONE; } split_point_start: // At split points actual search starts from here // Initialize a MovePicker object for the current position - MovePickerExt mp(pos, ttMove, depth, H, ss, (PvNode ? -VALUE_INFINITE : beta)); + MovePickerExt mp(pos, ttMove, depth, H, ss, PvNode ? -VALUE_INFINITE : beta); CheckInfo ci(pos); + pinned = pos.pinned_pieces(pos.side_to_move()); ss->bestMove = MOVE_NONE; futilityBase = ss->eval + ss->evalMargin; - singularExtensionNode = !Root + singularExtensionNode = !RootNode && !SpNode && depth >= SingularExtensionDepth[PvNode] - && tte - && tte->move() + && ttMove != MOVE_NONE && !excludedMove // Do not allow recursive singular extension search && (tte->type() & VALUE_TYPE_LOWER) && tte->depth() >= depth - 3 * ONE_PLY; @@ -896,25 +967,30 @@ split_point_start: // At split points actual search starts from here bestValue = sp->bestValue; } - // Step 10. Loop through moves - // Loop through all legal moves until no moves remain or a beta cutoff occurs + // Step 11. Loop through moves + // Loop through all pseudo-legal moves until no moves remain or a beta cutoff occurs while ( bestValue < beta && (move = mp.get_next_move()) != MOVE_NONE - && !Threads[threadID].cutoff_occurred()) + && !thread.cutoff_occurred()) { assert(move_is_ok(move)); + if (move == excludedMove) + continue; + + // At PV and SpNode nodes we want the moves to be legal + if ((PvNode || SpNode) && !pos.pl_move_is_legal(move, pinned)) + continue; + if (SpNode) { moveCount = ++sp->moveCount; lock_release(&(sp->lock)); } - else if (move == excludedMove) - continue; else moveCount++; - if (Root) + if (RootNode) { // This is used by time management FirstRootMove = (moveCount == 1); @@ -936,11 +1012,11 @@ split_point_start: // At split points actual search starts from here } // At Root and at first iteration do a PV search on all the moves to score root moves - isPvMove = (PvNode && moveCount <= (Root ? depth <= ONE_PLY ? 1000 : MultiPV : 1)); + isPvMove = (PvNode && moveCount <= (RootNode ? depth <= ONE_PLY ? MAX_MOVES : MultiPV : 1)); givesCheck = pos.move_gives_check(move, ci); - captureOrPromotion = pos.move_is_capture_or_promotion(move); + captureOrPromotion = pos.move_is_capture(move) || move_is_promotion(move); - // Step 11. Decide the new search depth + // Step 12. Decide the new search depth ext = extension(pos, move, captureOrPromotion, givesCheck, &dangerous); // Singular extension search. If all moves but one fail low on a search of @@ -949,7 +1025,8 @@ split_point_start: // At split points actual search starts from here // on all the other moves but the ttMove, if result is lower than ttValue minus // a margin then we extend ttMove. if ( singularExtensionNode - && move == tte->move() + && move == ttMove + && pos.pl_move_is_legal(move, pinned) && ext < ONE_PLY) { Value ttValue = value_from_tt(tte->value(), ss->ply); @@ -969,10 +1046,9 @@ split_point_start: // At split points actual search starts from here } // Update current move (this must be done after singular extension search) - ss->currentMove = move; newDepth = depth - ONE_PLY + ext; - // Step 12. Futility pruning (is omitted in PV nodes) + // Step 13. Futility pruning (is omitted in PV nodes) if ( !PvNode && !captureOrPromotion && !inCheck @@ -994,7 +1070,7 @@ split_point_start: // At split points actual search starts from here // Value based pruning // We illogically ignore reduction condition depth >= 3*ONE_PLY for predicted depth, // but fixing this made program slightly weaker. - Depth predictedDepth = newDepth - reduction(depth, moveCount); + Depth predictedDepth = newDepth - reduction(depth, moveCount); futilityValueScaled = futilityBase + futility_margin(predictedDepth, moveCount) + H.gain(pos.piece_on(move_from(move)), move_to(move)); @@ -1024,17 +1100,16 @@ split_point_start: // At split points actual search starts from here } } - // Bad capture detection. Will be used by prob-cut search - isBadCap = depth >= 3 * ONE_PLY - && depth < 8 * ONE_PLY - && captureOrPromotion - && move != ttMove - && !dangerous - && !move_is_promotion(move) - && abs(alpha) < VALUE_MATE_IN_PLY_MAX - && pos.see_sign(move) < 0; - - // Step 13. Make the move + // Check for legality only before to do the move + if (!pos.pl_move_is_legal(move, pinned)) + { + moveCount--; + continue; + } + + ss->currentMove = move; + + // Step 14. Make the move pos.do_move(move, st, ci, givesCheck); if (!SpNode && !captureOrPromotion) @@ -1043,21 +1118,16 @@ split_point_start: // At split points actual search starts from here // Step extra. pv search (only in PV nodes) // The first move in list is the expected PV if (isPvMove) - { - // Aspiration window is disabled in multi-pv case - if (Root && MultiPV > 1) - alpha = -VALUE_INFINITE; - - value = -search(pos, ss+1, -beta, -alpha, newDepth); - } + value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -beta, -alpha, newDepth); else { - // Step 14. Reduced depth search + // Step 15. Reduced depth search // If the move fails high will be re-searched at full depth. bool doFullDepthSearch = true; alpha = SpNode ? sp->alpha : alpha; - if ( depth >= 3 * ONE_PLY + if ( depth > 3 * ONE_PLY && !captureOrPromotion && !dangerous && !move_is_castle(move) @@ -1068,45 +1138,35 @@ split_point_start: // At split points actual search starts from here if (ss->reduction) { Depth d = newDepth - ss->reduction; - value = -search(pos, ss+1, -(alpha+1), -alpha, d); - + value = d < ONE_PLY ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -(alpha+1), -alpha, d); doFullDepthSearch = (value > alpha); } ss->reduction = DEPTH_ZERO; // Restore original reduction } - // Probcut search for bad captures. If a reduced search returns a value - // very below beta then we can (almost) safely prune the bad capture. - if (isBadCap) - { - ss->reduction = 3 * ONE_PLY; - Value rAlpha = alpha - 300; - Depth d = newDepth - ss->reduction; - value = -search(pos, ss+1, -(rAlpha+1), -rAlpha, d); - doFullDepthSearch = (value > rAlpha); - ss->reduction = DEPTH_ZERO; // Restore original reduction - } - - // Step 15. Full depth search + // Step 16. Full depth search if (doFullDepthSearch) { alpha = SpNode ? sp->alpha : alpha; - value = -search(pos, ss+1, -(alpha+1), -alpha, newDepth); + value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -(alpha+1), -alpha, newDepth); // Step extra. pv search (only in PV nodes) // Search only for possible new PV nodes, if instead value >= beta then // parent node fails low with value <= alpha and tries another move. - if (PvNode && value > alpha && (Root || value < beta)) - value = -search(pos, ss+1, -beta, -alpha, newDepth); + if (PvNode && value > alpha && (RootNode || value < beta)) + value = newDepth < ONE_PLY ? -qsearch(pos, ss+1, -beta, -alpha, DEPTH_ZERO) + : - search(pos, ss+1, -beta, -alpha, newDepth); } } - // Step 16. Undo move + // Step 17. Undo move pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); - // Step 17. Check for new best move + // Step 18. Check for new best move if (SpNode) { lock_grab(&(sp->lock)); @@ -1114,14 +1174,14 @@ split_point_start: // At split points actual search starts from here alpha = sp->alpha; } - if (value > bestValue && !(SpNode && Threads[threadID].cutoff_occurred())) + if (value > bestValue && !(SpNode && thread.cutoff_occurred())) { bestValue = value; if (SpNode) sp->bestValue = value; - if (!Root && value > alpha) + if (!RootNode && value > alpha) { if (PvNode && value < beta) // We want always alpha < beta { @@ -1133,9 +1193,6 @@ split_point_start: // At split points actual search starts from here else if (SpNode) sp->is_betaCutoff = true; - if (value == value_mate_in(ss->ply + 1)) - ss->mateKiller = move; - ss->bestMove = move; if (SpNode) @@ -1143,7 +1200,7 @@ split_point_start: // At split points actual search starts from here } } - if (Root) + if (RootNode) { // Finished searching the move. If StopRequest is true, the search // was aborted because the user interrupted the search or because we @@ -1154,15 +1211,15 @@ split_point_start: // At split points actual search starts from here break; // Remember searched nodes counts for this move - mp.rm->nodes += pos.nodes_searched() - nodes; + mp.current().nodes += pos.nodes_searched() - nodes; // PV move or new best move ? if (isPvMove || value > alpha) { // Update PV ss->bestMove = move; - mp.rm->pv_score = value; - mp.rm->extract_pv_from_tt(pos); + mp.current().pv_score = value; + mp.current().extract_pv_from_tt(pos); // We record how often the best move has been changed in each // iteration. This information is used for time management: When @@ -1170,43 +1227,50 @@ split_point_start: // At split points actual search starts from here if (!isPvMove && MultiPV == 1) Rml.bestMoveChanges++; - Rml.sort_multipv(moveCount); + // It is critical that sorting is done with a stable algorithm + // becuase all the values but the first are usually set to + // -VALUE_INFINITE and we want to keep the same order for all + // the moves but the new PV that goes to head. + Rml.sort_first(moveCount); - // Update alpha. In multi-pv we don't use aspiration window, so - // set alpha equal to minimum score among the PV lines. + // Update alpha. In multi-pv we don't use aspiration window, so set + // alpha equal to minimum score among the PV lines searched so far. if (MultiPV > 1) - alpha = Rml[Min(moveCount, MultiPV) - 1].pv_score; // FIXME why moveCount? + alpha = Rml[Min(moveCount, MultiPV) - 1].pv_score; else if (value > alpha) alpha = value; } else - mp.rm->pv_score = -VALUE_INFINITE; + // All other moves but the PV are set to the lowest value, this + // is not a problem when sorting becuase sort is stable and move + // position in the list is preserved, just the PV is pushed up. + mp.current().pv_score = -VALUE_INFINITE; - } // Root + } // RootNode - // Step 18. Check for split - if ( !Root + // Step 19. Check for split + if ( !RootNode && !SpNode && depth >= Threads.min_split_depth() && bestValue < beta - && Threads.available_slave_exists(threadID) + && Threads.available_slave_exists(pos.thread()) && !StopRequest - && !Threads[threadID].cutoff_occurred()) + && !thread.cutoff_occurred()) Threads.split(pos, ss, &alpha, beta, &bestValue, depth, threatMove, moveCount, &mp, PvNode); } - // Step 19. Check for mate and stalemate + // Step 20. Check for mate and stalemate // All legal moves have been searched and if there are // no legal moves, it must be mate or stalemate. // If one move was excluded return fail low score. if (!SpNode && !moveCount) return excludedMove ? oldAlpha : inCheck ? value_mated_in(ss->ply) : VALUE_DRAW; - // Step 20. Update tables + // Step 21. Update tables // If the search is not aborted, update the transposition table, // history counters, and killer moves. - if (!SpNode && !StopRequest && !Threads[threadID].cutoff_occurred()) + if (!SpNode && !StopRequest && !thread.cutoff_occurred()) { move = bestValue <= oldAlpha ? MOVE_NONE : ss->bestMove; vt = bestValue <= oldAlpha ? VALUE_TYPE_UPPER @@ -1216,7 +1280,8 @@ split_point_start: // At split points actual search starts from here // Update killers and history only for non capture moves that fails high if ( bestValue >= beta - && !pos.move_is_capture_or_promotion(move)) + && !pos.move_is_capture(move) + && !move_is_promotion(move)) { if (move != ss->killers[0]) { @@ -1230,7 +1295,7 @@ split_point_start: // At split points actual search starts from here if (SpNode) { // Here we have the lock still grabbed - sp->is_slave[threadID] = false; + sp->is_slave[pos.thread()] = false; sp->nodes += pos.nodes_searched(); lock_release(&(sp->lock)); } @@ -1244,9 +1309,12 @@ split_point_start: // At split points actual search starts from here // search function when the remaining depth is zero (or, to be more precise, // less than ONE_PLY). - template + template Value qsearch(Position& pos, SearchStack* ss, Value alpha, Value beta, Depth depth) { + const bool PvNode = (NT == PV); + + assert(NT == PV || NT == NonPV); assert(alpha >= -VALUE_INFINITE && alpha <= VALUE_INFINITE); assert(beta >= -VALUE_INFINITE && beta <= VALUE_INFINITE); assert(PvNode || alpha == beta - 1); @@ -1265,7 +1333,7 @@ split_point_start: // At split points actual search starts from here ss->ply = (ss-1)->ply + 1; // Check for an instant draw or maximum ply reached - if (ss->ply > PLY_MAX || pos.is_draw()) + if (pos.is_draw() || ss->ply > PLY_MAX) return VALUE_DRAW; // Decide whether or not to include checks, this fixes also the type of @@ -1304,8 +1372,6 @@ split_point_start: // At split points actual search starts from here else ss->eval = bestValue = evaluate(pos, evalMargin); - update_gains(pos, (ss-1)->currentMove, (ss-1)->eval, ss->eval); - // Stand pat. Return immediately if static value is at least beta if (bestValue >= beta) { @@ -1327,8 +1393,9 @@ split_point_start: // At split points actual search starts from here // to search the moves. Because the depth is <= 0 here, only captures, // queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will // be generated. - MovePicker mp(pos, ttMove, depth, H); + MovePicker mp(pos, ttMove, depth, H, move_to((ss-1)->currentMove)); CheckInfo ci(pos); + Bitboard pinned = pos.pinned_pieces(pos.side_to_move()); // Loop through the moves until no moves remain or a beta cutoff occurs while ( alpha < beta @@ -1366,7 +1433,8 @@ split_point_start: // At split points actual search starts from here } // Detect non-capture evasions that are candidate to be pruned - evasionPrunable = inCheck + evasionPrunable = !PvNode + && inCheck && bestValue > VALUE_MATED_IN_PLY_MAX && !pos.move_is_capture(move) && !pos.can_castle(pos.side_to_move()); @@ -1384,7 +1452,8 @@ split_point_start: // At split points actual search starts from here && !inCheck && givesCheck && move != ttMove - && !pos.move_is_capture_or_promotion(move) + && !pos.move_is_capture(move) + && !move_is_promotion(move) && ss->eval + PawnValueMidgame / 4 < beta && !check_is_dangerous(pos, move, futilityBase, beta, &bestValue)) { @@ -1394,12 +1463,16 @@ split_point_start: // At split points actual search starts from here continue; } + // Check for legality only before to do the move + if (!pos.pl_move_is_legal(move, pinned)) + continue; + // Update current move ss->currentMove = move; // Make and search the move pos.do_move(move, st, ci, givesCheck); - value = -qsearch(pos, ss+1, -beta, -alpha, depth-ONE_PLY); + value = -qsearch(pos, ss+1, -beta, -alpha, depth-ONE_PLY); pos.undo_move(move); assert(value > -VALUE_INFINITE && value < VALUE_INFINITE); @@ -1572,53 +1645,6 @@ split_point_start: // At split points actual search starts from here } - // extension() decides whether a move should be searched with normal depth, - // or with extended depth. Certain classes of moves (checking moves, in - // particular) are searched with bigger depth than ordinary moves and in - // any case are marked as 'dangerous'. Note that also if a move is not - // extended, as example because the corresponding UCI option is set to zero, - // the move is marked as 'dangerous' so, at least, we avoid to prune it. - template - Depth extension(const Position& pos, Move m, bool captureOrPromotion, - bool moveIsCheck, bool* dangerous) { - - assert(m != MOVE_NONE); - - Depth result = DEPTH_ZERO; - *dangerous = moveIsCheck; - - if (moveIsCheck && pos.see_sign(m) >= 0) - result += CheckExtension[PvNode]; - - if (pos.type_of_piece_on(move_from(m)) == PAWN) - { - Color c = pos.side_to_move(); - if (relative_rank(c, move_to(m)) == RANK_7) - { - result += PawnPushTo7thExtension[PvNode]; - *dangerous = true; - } - if (pos.pawn_is_passed(c, move_to(m))) - { - result += PassedPawnExtension[PvNode]; - *dangerous = true; - } - } - - if ( captureOrPromotion - && pos.type_of_piece_on(move_to(m)) != PAWN - && ( pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) - - pos.midgame_value_of_piece_on(move_to(m)) == VALUE_ZERO) - && !move_is_special(m)) - { - result += PawnEndgameExtension[PvNode]; - *dangerous = true; - } - - return Min(result, ONE_PLY); - } - - // connected_threat() tests whether it is safe to forward prune a move or if // is somehow connected to the threat move returned by null search. @@ -1627,7 +1653,7 @@ split_point_start: // At split points actual search starts from here assert(move_is_ok(m)); assert(threat && move_is_ok(threat)); assert(!pos.move_gives_check(m)); - assert(!pos.move_is_capture_or_promotion(m)); + assert(!pos.move_is_capture(m) && !move_is_promotion(m)); assert(!pos.move_is_passed_pawn_push(m)); Square mfrom, mto, tfrom, tto; @@ -1982,15 +2008,16 @@ split_point_start: // At split points actual search starts from here TTEntry* tte; int ply = 1; - assert(pv[0] != MOVE_NONE && pos.move_is_legal(pv[0])); + assert(pv[0] != MOVE_NONE && pos.move_is_pl(pv[0])); pos.do_move(pv[0], *st++); while ( (tte = TT.probe(pos.get_key())) != NULL && tte->move() != MOVE_NONE - && pos.move_is_legal(tte->move()) + && pos.move_is_pl(tte->move()) + && pos.pl_move_is_legal(tte->move(), pos.pinned_pieces(pos.side_to_move())) && ply < PLY_MAX - && (!pos.is_draw() || ply < 2)) + && (!pos.is_draw() || ply < 2)) { pv[ply] = tte->move(); pos.do_move(pv[ply++], *st++); @@ -2012,7 +2039,7 @@ split_point_start: // At split points actual search starts from here Value v, m = VALUE_NONE; int ply = 0; - assert(pv[0] != MOVE_NONE && pos.move_is_legal(pv[0])); + assert(pv[0] != MOVE_NONE && pos.move_is_pl(pv[0])); do { k = pos.get_key(); @@ -2053,9 +2080,9 @@ split_point_start: // At split points actual search starts from here } // Specializations for MovePickerExt in case of Root node - MovePickerExt::MovePickerExt(const Position& p, Move ttm, Depth d, - const History& h, SearchStack* ss, Value b) - : MovePicker(p, ttm, d, h, ss, b), firstCall(true) { + MovePickerExt::MovePickerExt(const Position& p, Move ttm, Depth d, + const History& h, SearchStack* ss, Value b) + : MovePicker(p, ttm, d, h, ss, b), cur(-1) { Move move; Value score = VALUE_ZERO; @@ -2064,7 +2091,7 @@ split_point_start: // At split points actual search starts from here // This is the second order score that is used to compare the moves when // the first orders pv_score of both moves are equal. while ((move = MovePicker::get_next_move()) != MOVE_NONE) - for (rm = Rml.begin(); rm != Rml.end(); ++rm) + for (RootMoveList::iterator rm = Rml.begin(); rm != Rml.end(); ++rm) if (rm->pv[0] == move) { rm->non_pv_score = score--; @@ -2072,17 +2099,6 @@ split_point_start: // At split points actual search starts from here } Rml.sort(); - rm = Rml.begin(); - } - - Move MovePickerExt::get_next_move() { - - if (!firstCall) - ++rm; - else - firstCall = false; - - return rm != Rml.end() ? rm->pv[0] : MOVE_NONE; } } // namespace @@ -2159,9 +2175,9 @@ void ThreadsManager::idle_loop(int threadID, SplitPoint* sp) { (ss+1)->sp = tsp; if (tsp->pvNode) - search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); + search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); else - search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); + search(pos, ss+1, tsp->alpha, tsp->beta, tsp->depth); assert(threads[threadID].state == Thread::SEARCHING);